The causes of land degradation can be divided
into natural hazards, direct causes, and underlying causes.
Natural hazards are the conditions of the physical environment
which lead to the existence of a high degradation hazard, for
example steep slopes as a hazard for water erosion. Direct causes
are unsuitable land use and inappropriate land management
practices, for example the cultivation of steep slopes without
measures for soil conservation. Underlying causes are the reasons
why these inappropriate types of land use and management are
practised; for example, the slopes may be cultivated because the
landless poor need food, and conservation measures not adopted
because these farmers lack security of tenure.

There is a distinction, although with overlap,
between unsuitable land use and inappropriate land management
practices.

Unsuitable land use is the use of land for
purposes for which it is environmentally unsuited for sustainable
use. An example is forest clearance and arable use of steeply
sloping upper watershed areas which would have more value to the
community as water sources, managed under a protective forest
cover.

Inappropriate land management practices refer
to the use of land in ways which could be sustainable if properly
managed, but where the necessary practices are not adopted. An
example is the failure to adopt soil conservation measures where
these are needed. It can also refer to land use which is
ecologically sustainable under low intensity of use but in which
the management becomes inappropriate at higher intensifies.
Examples are shifting cultivation and the grazing of semi-arid
rangelands.

The GLASOD assessment gives one or two causes
for each map unit and type of degradation. In this assessment,
only four causes were recognized, defined as:

de fore station and removal of natural
vegetation;

overgrazing;

agricultural activities;

over-exploitation of vegetation for
domestic use.

This survey did not recognize a separate class
of problems arising in the planning and management of irrigation,
but it is clear from the results that such problems are included
under agricultural activities.

The results from the GLASOD assessment of
causes is summarized in Table 20. Other information on causes is
from publications and persona! information.

TABLE 20 - Causes of degradation as
given in the GLASOD assessment

Type of degradation

Percentage area of degradation type caused by

Deforestation

Overgrazing

Agricultural
activities

Overcutting of
vegetation

Water erosion

61

67

2

44

Wind erosion

21

46

1

98

Soil fertility decline

25

0

75

0

Salinization

34

30

14

87

Waterlogging

0

0

85

33

Lowering of water table

12

22

65

34

All types of degradation

37

46

15

63

NB: Up to two causes are given for each type of
degradation, therefore percentages sum to more than 100.

plains and interior basins which restrict
outward drainage of groundwater;

soils which are naturally slightly saline.

For lowering of the water table:

semi-arid to aria climates with low rates
of groundwater recharge.

In some cases, these natural hazards are of
sufficient intensity to give rise to unproductive land without
human interference. Examples are the naturally saline soils which
occur in some interior basins of dry regions, or areas of natural
gullying ('badlands'). Such conditions have been referred to as
problem soils. Percentages of land covered by problem soils are
given in Dent (1990).

With respect to land degradation, the key
feature is that land shortage in the region has led to the
widespread agricultural use of areas with natural hazards. These
are the passive, or predisposing, conditions for land
degradation. Problem soils require special care in management,
and failure to give such care leads to land degradation.

Deforestation of unsuitable land Deforestation
is both a type of degradation as such, and also a cause of other
types, principally water erosion. Deforestation in itself is not
necessarily degrading without it, most productive agricultural
lands (in the temperate zone as well as the tropics) would not be
available. Deforestation becomes a cause of degradation first,
when the land that is cleared is steeply sloping, or has shallow
or easily erodible soils; and secondly, where the clearance is
not followed by good management.

The extent of deforestation considered as a
type of degradation has been summarized in Chapter 5, Section
Deforestation and forest degradation. It is the leading cause of
water erosion in steeply sloping humid environments. It is also a
contributory cause of wind erosion, soil fertility decline and
salinization.

Overcutting of vegetation Rural
people cut natural forests, woodlands and shrublands to obtain
timber, fuelwood and other forest products. Such cutting becomes
unsustainable where it exceeds the rate of natural regrowth. This
has happened widely in semi-arid environments, where fuelwood
shortages are often severe. Impoverishment of the natural woody
cover of trees and shrubs is a major factor in causing both water
erosion and wind erosion. In the GLASOD assessment it is cited as
a cause for 98% of the area affected by wind erosion. This
assessment also cites it as a contributory cause to salinization.

Shifting cultivation without adequate
fallow periods In the past, shifting cultivation was a
sustainable form of land use, at a time when low population
densities allowed forest fallow periods of sufficient length to
restore soil properties. Population increase and enforced
shortening of fallow periods has led to it becoming
non-sustainable. Shifting cultivation is found in the hill areas
of northeast India, where it is a cause of water erosion and soil
fertility decline.

Overgrazing. Overgrazing is
the grazing of natural pastures at stocking intensifies above the
livestock carrying capacity. It leads directly to decreases in
the quantity and quality of the vegetation cover. This is a
leading cause not only of wind erosion, but also of water erosion
in dry lands. Both degradation of the vegetation cover and
erosion lead to a decline in soil organic master and physical
properties, and hence in resistance to erosion.

Intense grazing at the end of the annual dry
season, and during periods of drought, does not necessarily lead
to degradation; the vegetation may recover during the succeeding
rains. Degradation occurs when the recovery of vegetation and
soil properties during periods of normal rainfall does not reach
its previous statue.

Non-adoption of soil-conservation
management practices Under arable use, management
practices are needed to check water erosion on all sloping lands.
In dry lands, measures to check wind erosion are necessary also
on lever land. Soil conserving management practices may be
grouped into:

Biological methods: maintenance of a
"round surface cover, of living plants or plant
litter; vegetative barriers, including both contour
hedgerows and grass strips; and windbreaks and
shelterbelts.

Great efforts have been made by soil
conservation services in the countries of the region to promote
the adoption of such management practices. In some areas, these
efforts have achieved a considerable measure of success. In
others, staff and resources have been greatly deficient, or
adoption of recommended methods poor. The recent change of
emphasis in soil conservation with more use of biological
methods, including agroforestry, and greater stress on farmers'
participation and economic incentives, has not yet been fully
taken up by extension services.

Often, it is not the environment nor the type
of land use which necessarily leads to degradation, but the
standard of management. A clear example is seen in tee production
in the hill lands of Sri Lanka. Well-managed farms maintain a
complete vegetation cover, which checks erosion even on steep
slopes; on poorly-managed farms, rainfall strikes bare soil
between plants, leading in places to very severe degradation.

Extension of cultivation onto lands of
longer potentiel and/or high natural hazards These are
also called 'fragile' or marginal lands. Historically the more
fertile, or high-potential, agricultural lands were the first to
be occupied. Population increase has led to the widespread use of
lands of longer potential, those which are less fertile or have
greater degradation hazards. Such marginal lands include:

steeply sloping land;

areas of shallow or sandy soils, or with
laterite crusts;

cultivation of semi-arid lands, and
grazing of the crier semi-arid areas, marginal to
deserts.

Such land is of great extent in the region, and
makes a large contribution to its agricultural production. Except
in areas of highest environmental hazards, e.g. upper watersheds,
it is neither desirable nor practicable that they should be taken
out of production. What must be recognized is that such lands
require higher standards of management if their resources are to
be conserved. Unfortunately, they are often utilized by poorer
farmers.

Improper crop rotations As a
result of population growth, land shortage and economic
pressures, farmers in some areas have adopted cereal-based,
intensive crop rotations, based particularly on rice and wheat,
in place of the more balanced cereal-legume rotations that were
formerly found. This is a contributory cause of soil fertility
decline.

Unbalanced fertilizer use Where
soil fertility has declined, as a result of prolonged cultivation
or erosion, farmers attempt to maintain crop yields. The primary
method available for doing so is application of fertilizer. In
the short term, a yield response is most readily and cheaply
obtained from nitrogenous fertilizer. There has been a steady
increase in the ratios of nitrogen to phosphorus, and nitrogen to
all other nutrients, in the region. Where phosphate deficiencies
have been recognized and counteracted by phosphatic fertilizer,
deficiencies of other nutrients, including sulphur and zinc, have
been reported.

The short-term measure of combatting fertility
decline by application only of macronutrients, and particularly
nitrogenous fertilizer, is leading to a greater problem of
nutrient imbalance in the medium term. Among the consequences is
likely to be longer yield responses to fertilizers.

Problems arising from planning and
management of canal irrigation The development of
salinization and waterlogging on the large-scale canal irrigation
schemes of the Indo-Gangetic plains has been frequently
described. Application of water in excess of natural rainfall led
to a progressive rise in the water table from the 1930s onward.
Where the water table has reached close to the surface,
waterlogging occurs leading, through evaporation of water
containing salts, to salinization. Sodification follows where
sodium replaces other bases in the soil exchange complex. The
problem could have been avoided, or reduced, if deep drains had
been included in the initial implementation of irrigation
schemes. More detailed accounts of the complex processes involved
will be found in development planning studies of Pakistan and
Indian irrigated areas.

Overpumping of groundwater In
areas of non-saline ('sweet') groundwater, the technology of
tubewells has led to abstraction of water in excess of natural
recharge by rainfall and river seepage. This has progressively
lowered the water table, as in Iran, India and Pakistan.

There are more basic reasons underlying the
reasons for land degradation outlined above. They apply to all
direct causes, other than the problems of large-scale irrigation
schemes which arose from lack of foresight in planning and
management.

Land shortage It has always
been recognized that land is a finite resource, but only recently
has the full impact of this fact occurred. In earlier times, food
shortage or poverty could be combatted by taking new, unused,
land into cultivation. Over most of South Asia, this solution is
no longer available. The percentage change in agricultural land
over the ten years 1980-1990 is under 2.5% for India, Pakistan,
Sri Lanka and Afghanistan, whilst for Bangladesh there has been a
small absolute decrease. The increase recorded for Nepal has
certainly been obtained by deforestation and taking into
agricultural use sloping land which is difficult to farm on a
sustainable basis.

When combined with increases in rural
population, land shortage has led to decreases in the already
small areas of agricultural land per person in six of the eight
countries, including all in the humid zone. The relative decrease
in land per person over 1980-90 was 14% for India and 22% for
Pakistan. In Iran, with a smaller rural population increase, the
land/people ratio has remained virtually constant.

There is almost no unused but usable land in
South Asia. All of the best land is already taken up, and that
which is not, cannot be used agriculturally on a sustainable
basis.

Land tenure: tenancy and open access
resources Farmers will be reluctant to invest in
measures to conserve land resources if their future rights to use
these resources are not secure. Two kinds of property rights lead
to this situation, tenancy and open access resources.

Despite efforts by legislation and land reform
programmes over many years, tenant occupation of farmland is
still very widespread. The landowner is now frequently from the
cities, and the land is farmed by tenants paying some form of
rental. Relations between landlord and tenant are often good, and
the tenant in fact remains on the same farm for many years.
However, such tenants lack the incentive to maintain the land in
good condition, being interested mainly in the immediate harvest.

Open access land resources are those which
anyone, in practice the poor and otherwise landless, can use,
without rights of continuing usufruct or tenure. This applies
mainly to forest lands, nominally under government ownership but
which are settled on a squatter basis.

There is a distinction between common property
and open access resources. In common property resources, use is
restricted to members of a community, village or clan, and is
subject to constraints, socially applied. For example,
pastoralists often have customs for when certain areas must be
rested from grazing, villages restrict the cutting of communal
woodland. On open access land there are no such constraints. With
no legal basis to their use, incentive to farm the land other
than for immediate needs is completely lacking. This is a serious
cause of deforestation followed by water erosion.

Economic pressures and attitudes Small
land holdings lead to severe economic pressures on farmers, to
obtain sufficient food and income to meet immediate needs.
Because of such pressure in the short term, labour, land and
capital resources cannot be spared to care for the land, for
example green manuring or soil conservation structures. This is
also the underlying reason for two other direct causes noted
above, improper crop rotations and unbalanced fertilizer use.

A contributory factor, not always appreciated
by outside observers, is a change in economic attitudes. In
former times, most farmers accepted the situation into which they
were bore, even if it was one of relative poverty. Modem
communications and influence have led to greater aspirations and
consequent requirements for income, thus increasing economic
pressures.

Poverty Countries of the
region have made great progress in economic development,
achieving increases in gross domestic product per capita. It is
questionable whether there have been corresponding improvements
in the real welfare of the rural poor. The majority of farmers
remain close to, or below, the margin of poverty, defined as
access to basic necessities of life.

Poverty leads to land degradation. It could
almost certainly be shown that richer farmers maintain their
soils in better state than poorer. Research based on sample
studies to confirm this is desirable.

Population increase Together
with land shortage, the second basic cause of degradation is the
continuing increase in rural, agricultural, population. Growth
rates for total population 19801990 for six countries range from
2.1-3.6% per year (for Afghanistan the figure is affected by
migration and war). Only in Sri Lanka have attempts to reduce the
rate of population increase made substantial progress, with a
growth rate of 1.4%.

Urban populations are increasing faster than
rural. The trend towards urbanization, however, is not sufficient
to reverse the key that absolute levers of rural population have
increased and are increasing. In Bangladesh, Bhutan, India, Nepal
and Pakistan, rural populations were 17-32% higher in 1990 than
in 1980. In absolute terms, the scale is greatest in India, where
already densely populated rural areas contained 79 million more
people in 1990 than 10 years earlier.

The direct and indirect causes of degradation
are linked by a chain of cause and effect, or causal nexus
(Figure 9).

The two external, or driving, forces are
limited land resources and increase in rural population.
Expressed another way, there are no longer substantial areas of
usable, unused land in the region; but the number of people to be
supported from this finite land resource is increasing every
year.

These two primary forces combine to produce
land shortage. This refers to increasing pressure of population
on land, resulting in small farms, low production per person and
increasing landlessness. A consequence of land shortage is the
next element, poverty.

Land shortage and poverty, taken together, lead
to non-sustainable land management practices, meaning the direct
causes of degradation. For reasons outlined above, poor farmers
are led to clear forest, cultivate steep slopes without
conservation, overgraze rangelands, make unbalanced fertilizer
applications, and the other causes noted above.

The non-sustainable management practices lead
to land degradation. This leads to reduced land productivity: a
lower response to the same inputs or, where farmers possess the
resources, a need for higher inputs to maintain crop yields and
farm incomes. This has the effect of increasing land shortage,
thus completing the cycle.

Case studies illustrating the interconnections
of this cycle are given in Asian Development Bank (1991).

There are two ways to check this cycle,
improved technology and reduction in population increase.
Improved technology could be added as a third external force in
Figure 1, divided into three elements:

land improvements (e.g. irrigation), which
can reduce land shortage;

increases in productive technology, which
can reduce poverty and pressure upon land;

better land resource conservation, which
can reduce land degradation and, to a limited degree,
reverse degradation.

Vast efforts have been made, by individual
farmers, national governments and through international
development assistance, to counteract the cycle of poverty and
land degradation by research and development of improved
technology. Much success has been achieved, as in the spread of
high-yielding crop varieties and use of fertilizers which was
(optimistically) called the 'green revolution'.

All of this effort will be nullified, and in
places reversed, if it is not accompanied by a reduction in rate
of growth of population. The existence of limited land resources
cannot be substantially changed. The other external force,
increase in population, constantly drives the cycle that leads to
poverty and land degradation.

Governments of the region, as well as
international agencies, recognize the priority of limiting
increase in population, as evidenced by reports. There is also
the beginning of an awareness that population questions cannot be
treated in isolation, but must be linked with sustainable land
development. What is significant is that recognition of the nexus
is found not just among land resource institutions or Ministries
of Agriculture, but widely within Asian development agencies, as
illustrated by the following quotations:

"It is population growth working in
conjunction with other factors that is bringing about widespread
environmental deterioration" (FAO/RAPA, 1990, p.10).

"Population issues currently encompass
areas of concern such as poverty alleviation, environmental
degradation...which are much broader than population size and
growth alone" (ESCAP, 1991a, para. 529).

"Few institutions have developed a
response strategy to the implications of population pressure on
natural resource management" (Asian Development Bank, 1991,
p.21).

"A significant reduction in population
growth rates is absolutely essential for visible improvements in
human development levers " (Asia Development Bank, 1990,
p.48).

Two views from outside the region may be added,
from the most recent FAO and World Bank reviews:

"A lack of control over resources;
population growth; a lack of alternative avenues of livelihood;
and inequity are all contributing to the degradation of the
regions's [Asia] resources. In turn, environmental
degradation perpetuates poverty, as the poorest attempt to
survive on a diminishing resource base" (FAO, 1992,
p. 106).

"The close link between poverty and
environmental problems makes a compelling case for increasing
assistance to reduce poverty and [to] slow population
growth...Rapid population growth can exacerbate the mutually
reinforcing effects of poverty and environmental damage. The
poor are both victims and agents of environmental damage" (World
Bank, 1992, pp. 3 and 7).

Statements recognizing the need to reduce
population for the welfare of their people have been made by all
governments of the region (e . g. ESCAP, 1987a) . In a regional
study of natural disasters and protection of the environment, a
summary table gives among causes of environmental problems,
"population" for five of the six South Asian countries
and "poverty" for four countries (SAARC, 1992, pp. 190-197).